Dolphin study yields fascinating findings BY NEEL KELLER | SENTINEL STAFF This pair of dolphins was spotted on a recent outing in the Roanoke Sound aboard the Nags Head Dolphin Watch ship. The Outer Banks Center for Dolphin Research conducts opportunistic field surveys aboard the ship. (Neel Keller | Sentinel) Ask Outer Banks visitors and residents alike to name their favorite local species of wild animal and it is almost certain to prompt two responses that far outnumber all the rest combined: the fabled wild ponies that roam Currituck County and the beloved dolphins that call the sounds and coastal waters of the Outer Banks home.The latter are being systematically tracked, researched, photographed and catalogued as part of the onoing photo-identification study of the Atlantic coastal bottlenose dolphins in the northern Outer Banks being conducted by the Outer Banks Center for Dolphin Research.Jessica Taylor, the center’s scientific advisor, moved to the Outer Banks in 2007 to work as a research assistant for the Nags Head Dolphin Watch, which had begun the study in 1997. Taylor had received her B.S. in Marine Sciences from Rutgers University and her master’s in Coastal Environmental Management from Duke University. During a year of study abroad at the University of Queensland in Australia, Taylor had fallen in love with studying bottlenose dolphins. She saw her chance to continue the study as a career and seized it, with no way of even guessing the excellent timing of her move to the Outer Banks.Rich Mallon-Day, now the center’s director of operations, had begun a dolphin research project in Cape May, NJ, then moved to the Outer Banks in 1997, founding the Nags Head Dolphin Watch to begin the first study of dolphins on the Outer Banks. With Taylor on board, Mallon-Day sold this business and founded the Center for Dolphin Research as a 501(C)(3) nonprofit organization to continue this study more intensively.The group’s mission statement explains, “We seek to learn more about the population abundances, movement patterns and behavior of coastal bottlenose dolphins in the Outer Banks and to expand public knowledge and concern for these marine mammals.”Taylor now conducts two kinds of research outings to continue the photo-identification study. “We do an opportunistic field survey on board the Nags Head Dolphin Watch ship,” she explained. This is a 41-foot covered pontoon boat that operates out of the Kitty Hawk Kites site on the Nags Head Causeway. It makes three dolphin watch trips daily, all open to the public. John Kerner, the center’s public relations advisor and now owner of Nags Head Dolphin Watch, pilots the ship. Taylor is the tour guide and resident dolphin expert.”We also do a dedicated field survey on board the center’s boat,” Taylor continued. “This is a 16-foot outboard owned by our director.” The difference between the types of surveys is that the dedicated field surveys aim to more systematically observe and document the dolphins. “The dolphin tours go out to areas where dolphin sightings have been recently reported,” said Taylor. “The dedicated field surveys follow a more systematic survey plan, with the goal of surveying the entire area.”One of our goals in the dedicated field surveys is to stay with a specific group of dolphins until everyone has been photographed and then to do a ‘focal follow,’ which means we pick a specific dolphin and follow him for up to two hours, recording his behaviors over time. This gives us a better picture of what a day in the life of a dolphin would be.”The group publishes its research in scientific journals and presents its findings at scientific conferences. The organization also collaborates with other marine mammal scientists at the N.C. Maritime Museum, the Duke University Marine Lab and the National Marine Fisheries Service to learn more about the dolphins’ long-range movement patterns.The dolphins are identified primarily by their dorsal fins, which bear such distinctive markings as notches and nicks. The latitude and longitude of the sighting are documented, along with the date and time and such environmental conditions as water temperature and salinity.”Dolphins have an interesting social structure,” said Taylor. “The social behavior of males and females is very different. While two adult males often form ‘pair-bonds,’ perhaps dating from friendships formed as calves in nursery groups, females most closely bond with their newborn calves. Females who have calves in nursery groups also spend time with other females with calves of similar ages.”Dolphins’ main diet is fish, and we have found that their favorites seem to be soniferous – or sound-producing – fish such as croaker, spot and weakfish.”The average life-span of a male is 40 to 45 years, and of a female is 50 to 55 years. This is based on the longest study, which has been conducted for 45 years in Sarasota, Florida.”Bottlenose dolphins are not an endangered species, but they have been depleted since a big ‘die-off’ in 1987, when many were stranding. Now we have the Marine Mammal Stranding Response, which can be called to rescue a dolphin found stranded.”While most of the dolphins are found in July and August in the Roanoke Sound, they are also found in the Pamlico, Croatan, Albemarle and Currituck Sounds. We estimate that 400 to 500 dolphins inhabit these sounds in the summer. We are seeking a grant to buy a larger boat to expand our survey into the ocean, where we think the dolphins who stay in the area from October to April may go.”Inhabiting warm and temperate seas around the world, bottlenose dolphins typically live in groups of 10 to 30, called pods. Upon encountering a shoal of fish, dolphins have been observed working as a team to herd the fish towards the shore to maximize the harvest.Dolphins also use echolocation, which is similar to sonar. Making clicking sounds, the dolphins listen for a return echo to determine the location and shape of nearby items, including potential prey.Bottlenose dolphins also use sounds for communication. These may include squeaks and whistles from the blowhole and sounds made through body movements, including leaping from the water and slapping their tails on the water surface.Research has shown that bottlenose dolphins are highly intelligent, as evidenced by such phenomena as mimicry, artificial language, object categorization and self-recognition. This high intelligence has led to military training and use for locating sea mines and detecting enemy divers. Dolphins have also been used by fishermen to drive fish into their nets. Dolphins continue to be hunted for food in some parts of the world and are also frequently killed inadvertently as a bycatch of tuna fishing.The species derives its common name from its elongated upper and lower jaws, which form a rostrum, or snout. The animal’s actual functional nose is the blowhole on top of its head.Dolphins are known for their acute eyesight. Their eyes are located at the sides of the head, and their double-slit pupils provide excellent vision both above and below the water.On the other hand, dolphins’ sense of smell is poor, due to the fact that the blowhole is closed when under water and opens only for breathing. It also has no olfactory nerves or olfactory lobe in the brain.A rare feature of the species’ high intelligence is their documented use of tools. Dolphins have been observed placing a marine sponge on their rostrum to protect it while searching for food on the sandy sea bottom.A unique movement demonstrated by the dolphins is “tail-walking”, in which they elevate the upper part of their bodies vertically out of the water while propelling themselves along the surface with powerful tail movements. This is considered mostly a learned behavior from human training, but it is thought to have been copied by other wild dolphins.Several large shark species, including the tiger shark, the dusky shark, the great white shark and the bull shark, prey on the bottlenose dolphins, especially calves. The dolphins are able to defend themselves by charging the predator. Swimming in pods also helps provide a defense against predators. Bottlenose dolphins also use evasive strategies to outswim their predators or “mobbing” to batter the predator to death or force it to flee.Dolphins often exhibit curiosity about nearby humans either in or near the water. They have been known to rescue injured divers by raising them to the surface. They also do this to help injured members of their own species.While their numbers are down, bottlenose dolphins are not considered endangered due to their abundance and adaptability. However, specific populations are threatened in some parts of the world due to various environmental changes.Dolphins are among the marine mammals protected by the Marine Mammmal Protection Act of 1972.The center periodically applies for research grants and conducts regular fund-raisers, including its annual Shrimp Cook-Off, which will be held in October at Ocean Boulevard. Membership is open to the public. More information is available at the center’s website, obxdolphins.org.